Electric lamp of double spiral convolution



June 21, 1949. A. GREINER ELECTRIC LAMP OF DOUBLE SPIRAL CONVOLUTION Filed Nov. 25, 1947 His Alrtorney.

Patented June 21, 1949 2,473,878 ELECTRIC LAMP or DOUBLE SPIRAL CONVOLUTION Alfred Grciner, Cleveland Heights, Ohio, assignmto General Electric Company, a corporation of New York 3 Claims. 1

My invention relates to electric lamps generally, and more particularly to lamps having elongated tubular envelopes. ticularly applicable to electric discharge lamps, especiallythe now well-known fluorescent lamps having long positive-column discharge paths and having their envelopes coated internally with fluorescent powders.

Such lamps are usually made in straight lengths, although lamps of simple circular shape have recently been made available. Other shapes, such as grids, spirals, etc., have been proposed but have not been manufactured commercially to any appreciable extent because of the difliculty and expense of manufacture. However, there are definite fields of use for such compact lamps, and it is therefore an object of my invention to make available a compact lamp of novel configuration. Another object is to provide a compact lamp of a configuration adapting it to manufacture on a mass production basis. Another object is to provide a compact lamp which is easily installed and which does not require a complicated fixture for its support.

Other objects and advantages of my invention will appear from the following description of species thereof and from the drawing.

In the drawing, Fig. 1 is a perspective view of an electric lamp comprising my invention; Fig. 2 is an elevation, in cross-section, of one end of the lamp and a suitable socket therefor; Fig. 3 is a front end view of the socket; Fig. 4 is a somewhat diagrammatic plan view of a fixture showing the arrangement of the sockets; and Fig. 5 is a perspective view of a lamp of modified configuration;

Referring to Fig. 1, the lamp comprising my invention has an elongated tubular' glass envelope I which is formed to a bifllarly coiled, or double helical, configuration wherein the midportion 2 of the envelope extends laterally across one end of the helix and the alternate turns 3 and 4 are coiled in the same direction. In the preferred form illustrated in the drawing the ends of the helix extend substantially tangentially of the coil and terminate in bases 5, 5 at diametrically opposite sides of the coil and substantially in a common plane normal to the longitudinal axis of the coil. The helix may be formed by coiling the heated glass tubing around a suitable drum as fully described and claimed in my copending application Serial No. 787,948, filed of even date herewith.

The lamp illustrated in Figs. 1 and 2 is of the fluorescent type wherein the envelope l is coated The invention is par- Application November 25, 1947, Serial No. 787,949

on its inner surface with fluorescent powder 6 and contains a filling of gas such as argon, neon, krypton, etc., and a small quantity of mercury 1 which, during operation of the lamp, furnishes a mercury vapor atmosphere of low pressure such as approximately 10 microns. The mercury vapor discharge emits ultraviolet radiations which excite the phosphor coating 6 to luminescence. Although any type of electrodes may be employed, I have illustrated the'thermionic, activated type which may comprise a coiled filament 8, preferably of tungsten wire coated with electron emissive oxides of alkaline earth metals. The electrode 8 at each end of the lamp ,is mounted on lead-in wires 8, 9 which extend exteriorly of the envelope I through a conventional stem to. The leads in are preferably twisted together and connected, as by solder, to a pin il projecting axially outward from the insulating shell l2 of the base 5. It will be obvious that, when desired, each base 5' is provided with two pins or prongs, the leads 9 in that case being separated and connected to individual pins.

The base pins II are in this case of collar buttonfldesign, being provided with an enlarged head portion I3 and engaging keyhole type contacts M in the. sockets I. It will be noted that the lamp, as shown in Fig. 2, is mounted in an inverted position from that shown in Fig. 1 so as to be suspended from the sockets I5.

Each of the sockets l5 comprises a body portion or housing It of suitable insulating material, such as a molded synthetic resin, having a longitudinally extending oval cavity i'l therein. The cavity I! has its axis at a small. angle to the front face l8 of the socket, the said angle corresponding with the pitch angle of the turns of the helically coiled lamp. The contact I4 is supported in said cavity by a U-shaped bracket I9 which is attached to an insulating disc 20 of substantially the same shape and size as cavity H, the said disc being, in turn, secured to the rear wall 2| of the housing It. The contact I4 is secured to bracket 19 by integral lugs or pins 22 projecting from the leg portions of said bracket and peened or riveted in apertures in said contact I. The contact portion of the socket also includes a U-shaped spring member 23 having one leg portion secured to the bracket l9, and having its free leg portion located behind the keyhole aperture 24 in contact ll. The edge of the smaller, lower portion of the keyhole slot 24 is chamfered or bevelled rearwardly (Fig. 2) to provide a seat for the bevelled or sloping under-side 25 of the pin head iii. The socket 3 may be mounted by means of an L-shaped contact prong 26 which is secured to bracket l9 by screw 21 and extends upwardly through a slot or aperture 28 communicating with the cavity ll.

As shown in Fig. 4, the sockets I are spaced apart on a suitable mounting support 29 with their open forward ends 18 substantially in a common plane and facing in opposite directions. The lamp is mounted in the sockets by presenting its bases 5, 5 to the sockets and then rotating the lamp a slight amount so that the pins I3 enter the cavity and pass through the enlarged upper ends of the keyhole slots 24 against the springs 23 whereupon the lamp is moved downward slightly so that the necks of the pins I3 drop into the constricted lower ends of the slots 24, thereby locking the lamp in place.

The lamp I shown in Fig. 5 is similar to-that shown in Fig. 1 except that it is coiled in the form of a conical double helix rather than the cylindrical double helix of Fig. 1.

It will be apparent that the configuration of the lamps in accordance with my invention provides a compact light source while retaining the high efficiency of the long positive-column discharge path. In one advantageous form, for example, a lamp of one inch diameter tubing and eight feet long is coiled into a double helix of twelve inch diameter.

What Iclaim as new and desired to secure by Letters Patent of the United States is:

1. An elongated tubular electric lamp of bifilarly coiled configuration, having its ends extending substantially tangentially of the coil and terminating at diametrically opposite sides of the coil substantially in a common plane normal to the longitudinal axis of the coil with said ends facing in opposite directions, and bases on said ends having socket engagement means thereon.

2. An elongated tubular electric lamp of bifilarly coiled configuration, having its ends extending substantially tangentially of the coil and terminating at diametrically opposite sides of the coil substantially in a common plane normal to the longitudinal axis of the coil with said ends facing in opposite directions, and bases on said ends having socket engagement pins with enlarged outer ends and projecting endwise therefrom.

3. In combination, an elongated tubular electric lamp of bifilarly coiled configuration, having its ends extending substantially tangentially of the coil and terminating at diametrically opposite sides of the coil substantially in a common plane normal to the longitudinal axis of the coil with said ends facing in opposite directions, and bases on said ends having socket engagement means projecting endwise therefrom, and mounting means including a pair of sockets e'ach comprising a housing having in its front face an opening for receiving a lamp base, said sockets being disposed with their faces substantially in a common plane and facing in opposite directions and being spaced apart to receive the lamp bases upon presentation of said bases before the openings in said sockets followed by a slight rotation of the lamp about its axis.

ALFRED GREINER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 702,314 Moore June 10, 1902 1,870,147 Smally Aug. 2, 1932 1,926,552 Morgan Sept. 12, 1933 2,117,756 Douglas May 17, 1938 2,267,318 Aicher Dec. 23, 1941 2,392,661 Greiner Jan. 8, 1946 FOREIGN PATENTS Number Country Date 268,046 Great Britain Mar. 28, 1927 513,715 Great Britain Oct. 19, 1939 

